Unfortunately I haven't had much time to play with the early Beta of SQL 2005.  However, from what I have seen and heard, the locking will remain largely the same with one addition.  Database views (at least that's the name that was being used when I last heard them discussed) preserve the database as it existed at a given point in time without being a full copy.  Queries against the database view will be satisfied by looking at the "live" data unless the view contains some changes.  This isn't quite the same thing at Oracle's Rollback Segments but it sounds like it might be a good "split the difference" sort of solution.  I will point out again that I haven't actually used this functionality and I don't know the details of what this will mean for transactions and Locking...